add ready prop to autosize hook

client/ui/frontend/src/hooks/useAutoSizeWindow.ts

@@ -22,7 +22,16 @@ import i18next from "@/lib/i18n";
 // the observer can settle on a stale size before React's commit and the
 // font's glyph metrics finish updating. An explicit double-rAF after the
 // language flip guarantees the final layout is the one we measure.
-export function useAutoSizeWindow<T extends HTMLElement>(width: number) {
+//
+// `ready` (default true) gates Window.SetSize + Window.Show. Pass false
+// while the caller is still resolving its initial content (e.g. waiting
+// on an async probe) so the window stays Hidden instead of briefly
+// rendering placeholder padding at the wrong size — Linux/GNOME in
+// particular paints whatever the frame ends up at, and a transient
+// half-height frame can leak through. Flip ready=true once the real
+// content is in the DOM; the effect re-runs, measures the final size,
+// and shows the window.
+export function useAutoSizeWindow<T extends HTMLElement>(width: number, ready: boolean = true) {
     const ref = useRef<T | null>(null);
     useLayoutEffect(() => {
         const el = ref.current;
@@ -31,6 +40,7 @@ export function useAutoSizeWindow<T extends HTMLElement>(width: number) {
         let raf1 = 0;
         let raf2 = 0;
         const apply = () => {
+            if (!ready) return;
             const h = Math.ceil(el.getBoundingClientRect().height);
             if (h <= 0) return;
             // Wails Window.SetSize takes the *frame* size on every platform
@@ -79,6 +89,6 @@ export function useAutoSizeWindow<T extends HTMLElement>(width: number) {
             cancelAnimationFrame(raf2);
             i18next.off("languageChanged", scheduleApply);
         };
-    }, [width]);
+    }, [width, ready]);
     return ref;
 }

client/ui/frontend/src/modules/welcome/WelcomeDialog.tsx

@@ -51,10 +51,13 @@ type InitialState = {
 };
 
 export default function WelcomeDialog() {
-    const contentRef = useAutoSizeWindow<HTMLDivElement>(WINDOW_WIDTH);
     const [step, setStep] = useState<WelcomeStep>("tray");
     const [initial, setInitial] = useState<InitialState | null>(null);
     const [closing, setClosing] = useState(false);
+    // ready=false until the daemon probe resolves — keeps the window
+    // Hidden so neither the empty padding-only frame (Linux/GNOME paints
+    // through) nor a placeholder div leaks onto screen.
+    const contentRef = useAutoSizeWindow<HTMLDivElement>(WINDOW_WIDTH, initial !== null);
 
     // Probe daemon state on mount: who's the active profile, do they
     // have an email recorded, and what management URL is configured?
@@ -171,11 +174,7 @@ export default function WelcomeDialog() {
 
     const content = useMemo(() => {
         if (!initial) {
-            // Probe in flight — render an empty container so the dialog
-            // window measures something tiny instead of flashing the
-            // tray step before we know whether step 2 applies. The probe
-            // completes within a single tick on a healthy daemon.
-            return <div className={"h-32"} />;
+            return null;
         }
         switch (step) {
             case "tray":